This invention pertains to releasable sealing couplings which provide a remote end-to-end joinder of two off-set but generally parallel metal tubular conduits. This invention also pertains to such releasable sealing couplings for use in tubular conduits carrying a liquid metal, particularly liquid sodium, wherein the conduits are submerged in a bath of the liquid metal. Further, the invention relates to a fast safety test reactor incorporating such a coupling in a crowded portion thereof.
It is an object of the present invention to provide a space-efficient sealing coupling that can be operated at a distance remote from the coupling. One example of such remote operation is the coupling joinder of fuel rod elements in the lower portion of a metal-cooled nuclear reactor core. This area of the reactor is not accessible for direct manipulation by man or machine, due to crowded space conditions, as well as high temperature and radiation levels. Because of the liquid metal environment, and especially when the liquid metal comprises sodium, the use of conventional sealing materials such as rubber, plastic, and most metals is precluded. Accordingly, it is another object of the present invention to provide a remote coupling for use in a liquid metal, and in particular a liquid sodium environment.
While affording a flexible connection between misaligned tubular conduits, the coupling must have a self-limiting deflection to prevent further lateral displacement of an unstable remotely located conduit such that the sealing coupling cannot be initiated or maintained. Accordingly, it is another object of the present invention to provide such a self-limiting coupling.
A tank-type liquid-metal-cooled nuclear reactor includes a reactor core comprised of a closely-spaced array of elongated tubular fuel assemblies that are installed and removed in vertical directions, through a precisely-dimensioned access port of minimal size which is located in the top of the reactor tank. Separate coolant circuits of liquid metal are maintained in the tank and in each individual fuel assembly. Current techniques for monitoring reactor operation require diagnostic equipment located in an upper extension of the fuel assembly housing. This equipment is located downstream in an upwardly-directed coolant flow which has passed over lower fuel assembly sections. An intermediate sealing coupling is required to join upper and lower sections of the fuel assembly housing. Several problems arise if the sealing coupling either constricts internal cooling flow, or overlies the outer dimensions of the fuel assembly housing. Accordingly, it is another object of the present invention to provide a fluid-tight releasable, thin-walled, flexible coupling that does not exceed the external diameters of the pipes to which it is connected, and which does not reduce the cross-sectional area required for internal flow conditions.
Additional objects, advantages and novel features of the invention will be set forth in part in the description which follows, and in part will become apparent to those skilled in the art upon examination of the following or may be learned by practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.